In the last few years, mostly thanks to “Inherent Vice,” Katherine Waterston has made the shift from struggling actor to an “It” girl. In fact when we speak she’s in London shooting the J.K. Rowling-penned “Fantastic Beasts and Where to Find Them.” “I feel like I’m on the backlot at Paramount in 1950 and Elizabeth Taylor’s going to come around the corner,” she says. Right now, though, she’s promoting another major release: “Steve Jobs,” the Aaron Sorkin-written account of the late Apple icon (played by Michael Fassbender), which relates the frenzied build-up to three of his most significant product launches. Waterston plays Chrisann Brennan, an ex who’s justifiably furious with him, as he doesn’t want to claim paternity of the young girl they had together.

The move to major productions must be jarring. How have you dealt with it?

It’s not really as much of a shift as I probably imagined when I would be fantasizing about having a proper career. [Laughs] You don’t know what you’re doing and it all comes together at the last minute.

I think a lot of us wind up doing things we never expected and learning as we go along.

Exactly. You find yourself doing things you’ve never done before when you’re doing low budget independent films. You have to hold the boom or become the art department. When we did “Queen of Earth,” we didn’t have a continuity person. We had photographs and notes and we’d have to look at the notes to figure out what outfits to put on for every scene. Which is actually completely doable when you realize how little thinking you have to do as an actor, apart from what you have to do in a scene on any given day. It’s not impossible to have a few other thoughts in your head. It’s galvanizing, really, when you have to participate in that way. You feel more a part of it in a way and responsible for it. But it’s also fun to have a two-day weekend.

“Steve Jobs” has this feeling of controlled chaos. What was it like being in the middle of that?

That’s supposing something that wasn’t really my experience. I didn’t feel it was particularly controlled or particularly chaotic while I was working on it. It felt more like we were chipping away at something. When you’re shooting a scene you’re just trying to find everything that’s in it, especially when you have such good writing. When a scene is really well-written it’s like, “Ok, I don’t know what’s in there but I know enough to know there’s a lot in there. And how much am I going to be able to find before they call cut?” I’m glad it felt chaotic. That’s a testament to Danny [Boyle]’s skill [as director]. I haven’t seen the movie yet, but I’m glad you’re describing it that way.

Speaking of the writing, Sorkinese seems like it might be daunting to speak.

The only part that was terrifying was when I was auditioning and I thought, “Am I anywhere near good enough to speak these words?” But actually it’s so much scarier to try and make poor writing sound good than it is to play around with really, really great dialogue. This is just like getting shot out of a cannon. You’re supported by such a great structure. There’s so much humor and intelligence. And a great rhythm. The writing does so much of your performing for you that you can relax, in a way. I would have thought, “Oh my god, I’ll be a ball of nerves, I’ll be so paranoid about getting that comma right or did I pause there? Did I cut him off in time?” But he writes the way people think.

It’s unusually articulate, especially for mainstream dialogue.

It doesn’t dumb anything down for the audience. And guess what? They love it. They can follow it.

This isn’t a traditional biopic, so we don’t see all of Brennan’s history with Jobs. How do you handle only suggesting a character’s entire history in fragments?

One thing I was thinking about was, how do I show the audience that this is an old dynamic, this is an old relationship? She’s had some of these arguments before. I had to make sure it didn’t feel fresh, that it felt like a worn-out relationship. It’s so much more a portrait than a biopic. You want to get to the essence of things because you don’t have the standard and, in my opinion, quite boring story structure of seeing their early problems, then later they split up, and so on. You don’t go through it the dull way. But you still have the responsibility to tell that history in the scenes I have.

More traditional biopics tend to simplify, but ones like this, that dwell on specific times in real people’s lives, get to do more of a deep dive and explore more truths.

I think it’s much more responsible reporting, in a way. A lot of these biopics make us feel like we really know someone, and that’s a dangerous thing to do to the public. Because it’s never really true. You see these biopics where one dramatic thing happens after another, and this is why they became the artists they became, because of that one thing. No human I have ever met has ever had that experience — that one moment. They’re a little irresponsible and deceptive. It’s best to give someone a feeling of something.

He was alive when [Walter] Isaacson wrote this biography [also called “Steve Jobs”]. [Jobs] and his wife told Isaacson they wanted it to be a complete portrayal. Don’t surgarcoat everything. That’s why it’s interesting. He’s a dynamic, complicated person, flawed and brilliant and unpredictable. I absolutely feel it would be a more boring story if we dragged him through the mud. And it wouldn’t be responsible. He wasn’t simply a baddie.

Danny Boyle seems an outside-the-box choice of director, as his films tend to be very heavy on visuals.

All of us knew we had to make the words work. None of us were trying to add bells and whistles, because it didn’t need them. [Boyle]’s smart enough to know that. But he’s just a really great leader. He kept the energy up on set. That sounds like a dumb thing, but it really makes a difference when you’re freaking out about your own performance and trying to rise to the occasion and you’ve been working eight, nine hours. He maintained the urgency, and he did that with a smile on his face. Again, that seems like, “Who cares?” But this is all difficult stuff we do, as actors, and to feel that support is almost everything.